There are generally two categories of green wall systems: green facades and living walls. A green facade is a wall covered with climbing vegetation, for example, vines. In green façade systems, there may be a screen or trellis structure that provides a structure for climbing plants to grow on, rather than allowing those plants to adhere directly to the building envelope. Green facades generally root the plants in the ground, although some systems include planters with elevated root containers interstitially mounted to the structural wall. Green facades are exterior green wall systems. Green facades are generally only used for exterior applications.
Conversely, a living wall is a wall covered with vegetation with the plants (and roots) contained in growing media contained within the wall itself. The plants used in a living wall are not limited to climbing plants such as vines, but may also include many more plant options depending on application and climate. The visual effect of a living wall system is to create a tapestry of greenery. Living wall systems can be installed in both interior and exterior applications.
Prior art living wall systems generally include one or more of the following layers (from structural wall outwards): waterproof barrier, structural support and fasteners, irrigation tubing and system, drainage elements, growing media containment element(s), retention or capillary fabric, growing media, plants, and supplemental lighting (for interior and low-light applications). Different prior art living wall systems may vary the order of these layers and composition of each layer according to the design intent, application, and vendor of the green wall.
Prior art living wall systems may be constructed either by placing each layer one at a time: mounting structural components, arranging drainage elements, assembling irrigation system, unrolling and mounting retention fabrics, distributing growing media and planting individual plants; or by pre-growing modular elements in a greenhouse, where the modules may be filled with growing media and plants, and adhering these modules to the structural wall once irrigation and drainage elements are constructed.
Living wall systems have various methods for containing growing media. In the layer-by-layer systems, retention fabrics may be attached to structural wall in pinches, rather than flat, to create pockets where a small amount of growing media is inserted and individual plants may be planted. In modular systems, there may be various methods. One method uses felt bags filled with growing media and planted. Another method uses plastic or metal frames lined with filter fabric and filled with growing media; plants may be planted in horizontal units and the unit is grown at the greenhouse at gradually steeper slopes until the units are vertical or near vertical. A third method uses a rigid growing media (such as rock wool) that is formed like a cupcake pan, with individual plant root balls inserted in each ‘cupcake’ space, and grown at a greenhouse at gradually steeper slopes until the units are vertical. For these methods for growing media containment in living wall systems, the rooting environment consists of isolated units of growing media, the plant growth potential is limited to the space directly out in front of the wall because plants above shade plants below, and the replacement plants for plants that die may be at a disadvantage for establishment because the young replacement plants must establish themselves in a vertical growing environment, rather than horizontal and gradually steeper until vertical.